Abstract
Abstract: :
Purpose: To characterize gene expression pattern in the human trabecular meshwork (TM) and identify candidate genes for glaucoma by expressed sequence tag (EST) analysis. Methods: RNA was extracted from dissected human TM and used to construct unamplified, un-normalized cDNA libraries in the pSPORT1 vector. Over 4000 clones were sequenced from their 5’end. Clones were clustered and identified using the GRIST software. In addition, the expression patterns of genes encoding olfactomedin-domain proteins were analyzed by RT-PCR. Results: After removing non-mRNA contaminants, 3459 independent TM-expressed clones were obtained. These grouped into 1888 clusters, potentially representing individual expressed genes. Transcripts for the myocilin gene, a locus for inherited glaucoma, formed the third most abundant cluster in the TM collection, while several other genes implicated in glaucoma (PITX2, CYP1B1 and optineurin) were also represented. One abundant TM transcript was from the gene for the angiopoietin-like factor CTD6, which is located at chromosome 1p36.2-p36.1 in the region of the glaucoma locus GLC3B, while other transcripts were from genes close to known glaucoma loci. The TM collection contained cDNAs for genes that are preferentially expressed in the lymphatic endothelium (matrix Gla protein, apolipoprotein D precursor, selenoprotein P precursor). In addition to EST profiling, RT- PCR was used to detect transcripts of the olfactomedin-domain proteins latrotoxin receptor Lec3 and optimedin in the TM. Conclusions: The TM libraries were a good source of molecular markers for TM and candidate genes for glaucoma. The abundance of myocilin cDNAs corresponded to the critical role of this gene in glaucoma and contrasted with libraries derived from cultured tissue. Our expression profile analysis raises the possibility that cells of the TM and Schlemm’s canal may be more similar to lymphatic, rather than blood vascular endothelium.
Keywords: gene/expression • genetics • anterior segment